The present invention generally relates to a measurement system and a method for determining a change of capacitance of an electrode assembly that may be exposed to specified environmental conditions so that, for example, the presence of a specified substance results in a modified capacitance due to a change in relative permittivity.
In many fields, exact and fast information about the specific environmental conditions are required so as to initiate an appropriate response to the detected environmental conditions. For instance, an adequate assessment of the environmental conditions on road surfaces may significantly contribute to enhanced traffic safety, since corresponding decisions made by road administrators and surfaces may be based on this information. Moreover, information regarding the surface conditions may also be relayed to road users by means of broadcasting and electronic signs, thereby enabling the adaptation of speed limits driving style to currently prevailing road conditions. In particular, any information on road sections having ice or moisture formed thereon may help to significantly improve traffic safety. Thus, one of the key components of modern road information systems (RIS) is the monitoring of the current road surface conditions, wherein the detection of the presence of water, snow, ice and the beginning formation of ice, is one of the most important pieces of information for traffic safety. Based on the measurement data, critical information such as the possibility of aquaplaning or ice layers on the road surface can be determined in time and thus appropriate precautions may be taken.
The environmental conditions within a specified area may also be important in other fields such as ice formation on airplane wings, the gathering of reliable meteorology data, including the presence of ice, moisture, water, and the like on specific surfaces, as well as the detection of dangerous substances, such as fuels or ammoniac within specified areas. However, the efficiency of any system for detecting the presence or state of a specified substance strongly depends on the reliability of the measurement data, as, for instance, an erroneous indication of water instead of ice may even increase the probability of traffic accidents rather than provide for enhanced traffic safety. Moreover, a road information system may require the provision of a large number of individual surface detectors so that a high degree of reliability with respect to premature device failure, effort in view of maintenance as well as cost effectiveness of the individual sensor elements represent important criteria.